The present invention relates generally to the bearing art, and more particularly concerns dripless bearings, especially dripless journal bearings.
In general, bearings can be divided into two basic categories, rolling element bearings and sliding contact bearings. Among the rolling element bearings, for example, are ball and/or roller bearings, which typically have very little friction but tend to fatigue under substantial loads. Rolling element bearings are also usually quite expensive and hence are generally not preferred for that reason as well.
Sliding contact bearings are further classifiable into two basic groups, the first being those which operate either hydrodynamically or by a squeeze film, and those which do not, such as powdered metal bearings and bushings.
An example of the hydrodynamic class of bearings, into which the present invention can be classified, is the traditional journal bearings, such as those used in internal combustion engines. In the journal bearing, the shaft and the bearing are separated by a film of lubricant, so that the bearing does not come into contact with the shaft, except perhaps when the two are at rest.
The hydrodynamic journal bearing has many desirable characteristics, among them being a very long life, and the capability of withstanding high loads, without high expense. For instance, hydrodynamic bearings can typically carry approximately 20 times the load that boundary lubricated bearings can carry.
Such superior operating characteristics would ordinarily make such bearings the first choice in a wide variety of bearing applications. However, the number of applications for hydrodynamic journal bearings has been heretofore severely limited, because a significant amount of bearing lubricant escapes from the bearing during normal operation. Hence, the exterior surface of the bearing, as well as any immediate surrounding surfaces, tend to become coated with the lubricant. In addition, such leakage mandates a lubricant reservoir, for replacement of the lost lubricant, adding expense to the bearing installation, and increasing the bearing's space requirement.
Accordingly, a general object of the present invention is to overcome one or more of the disadvantages of the prior art noted above.
It is a further object of the present invention to provide a bearing which does not drip lubricant.
It is another object of the present invention to provide such a bearing which is capable of breathing without discharging lubricant.
It is an additional object of the present invention to provide such a bearing which is capable of drawing externally applied lubricant into the bearing while inhibiting lubricant flow in the opposite direction.
It is a still further object of the present invention to provide such a bearing which is capable of retrieving, by capillary action, lubricant which has been squeezed out the ends of the bearings.